Center-pull napkin dispenser with controlled wrinkling

ABSTRACT

Center-pull napkin dispensers and methods of supplying napkins for the same are disclosed. A center-pull napkin dispenser may comprise a body for supporting at least one roll of perforated paper napkins and a nozzle comprising a nozzle opening configured for dispensing napkins therethrough. The nozzle opening defines a nozzle cross-sectional area (A N ) and the roll of paper napkins defines a cross-sectional material mass (X). The nozzle cross-sectional area divided by the cross-sectional material mass and multiplied by a constant C=10,000, is about (A N /X)*C≧0.85. A method of supplying napkins for a center-pull napkin dispenser may comprise the steps of providing a center-pull napkin dispenser comprising a nozzle opening that defines a nozzle cross-sectional area (A N ); providing a roll of paper napkins such that the nozzle cross-sectional area divided by the napkin cross-sectional material mass (X) multiplied by the constant, is about (A N /X)*C≧0.85. An objective wrinkle index is also disclosed.

BACKGROUND

Various paper napkin dispensers are known in the art. A common napkin dispenser includes a stack of folded napkins that are spring-biased against a dispensing slot. However, these dispensers may not allow a user to dispense a napkin without needing to touch the dispenser. Furthermore, these dispensers are inefficient, often dispensing multiple napkins at once. Also, given that in some situations it is important for a user to secure a napkin quickly and easily, the known dispensers often fail to provide satisfactory service for a variety of applications. Further, known napkin dispensers can require frequent refilling of napkins.

Dispensers for paper towels are also known in the art. These paper towel dispensers can take the form of center-pull dispensers, which include a body containing a roll of paper towels. The paper towels form a continuous web and are defined by lines of perforations extending across the web. The web at the center of the roll is initially fed through a nozzle such that a tail extends through the nozzle for a consumer to pull. The consumer pulls the tail and the web tears along a line of perforation, thus dispensing paper towels.

However, prior art paper towel dispensers are not usable for dispensing napkins given the high degree of wrinkling imparted to the paper towels. As the paper towel is drawn through the nozzle, its cross-sectional shape is changed from generally planar to highly contorted web, which creates wrinkling that remains in the paper towel after it has been dispensed. For paper towel applications, this is acceptable to the consumer. However, for napkins, the consumer often eats a meal with the napkin lying in a flat unwrinkled state, and as the napkin is used by the consumer, it becomes more crumpled and wrinkled. Napkins that are highly wrinkled before use are less desirable to the consumer, perhaps due to an impression that the napkin has been previously used.

Thus, there is a need for an easy to use, efficient napkin dispenser that dispenses with a controlled amount of wrinkling.

BRIEF SUMMARY

These and other advantages are met by the various embodiments of the present invention, which includes a center-pull napkin dispenser. In various embodiments, a center-pull napkin dispenser with a controlled napkin wrinkle index is disclosed. In various embodiments, the center-pull napkin dispenser may comprise a body that may be configured to accommodate at least one roll of napkins configured for being dispensed via the center-pull napkin dispenser. The center-pull napkin dispenser may also comprise a nozzle configured for dispensing a paper napkin. The nozzle may comprise an opening configured for dispensing the napkins from the at least one roll of napkins. The nozzle opening defines a nozzle cross-sectional area (A_(N)). The roll of paper napkins defines a cross-sectional material mass (X). The nozzle cross-sectional area (A_(N)) defined by the nozzle opening and the cross-sectional material mass (X) defined by the roll of paper napkins, are configured such that their ratio defines a nozzle-paper ratio, A_(N)/X, that, in various embodiments is above a minimum value.

In other embodiments, a method of supplying paper napkins for a center-pull napkin dispenser is disclosed. In various embodiments, a method of supplying paper napkins for a center-pull napkin dispenser and controlling the wrinkle index of napkins dispensed by the center-pull napkin dispenser is disclosed. In various embodiments, at least one center-pull napkin dispenser may be provided. In various such embodiments, the at least one center-pull napkin dispenser may comprise a nozzle configured to dispense paper napkins from at least one roll of napkins. In such embodiments, the nozzle may comprise an opening disposed within the nozzle and may be configured for dispensing paper napkins. The opening of the nozzle may define a nozzle cross-sectional area (A_(N)). In various embodiments, the paper supplied for a center-pull napkin dispenser may define a cross-sectional material mass (X). In various embodiments, the paper supplied for the center-pull napkin dispenser may have a cross-sectional material mass (X) such that the ratio of the nozzle cross-sectional area (A_(N)) to the cross-sectional material mass (X) defines a nozzle-paper ratio, A_(N)/X, that is, in various embodiments, above a minimum value.

Additionally, an objective method of determining the amount of wrinkling experienced by a dispensed napkin is provided, in various embodiments. In various embodiments, this wrinkle index (W) may take into account the number of wrinkles in a napkin, the size of wrinkles in a napkin, the depth of wrinkles in a napkin, and/or other parameters.

In various embodiments, a center-pull type dispenser for dispensing paper napkins is provided. In various such embodiments, the dispenser comprises: a body for supporting at least one roll of perforated paper napkins, the paper napkins defining a scaled web cross-sectional material mass (X); and, a nozzle operatively connected to the body for dispensing the paper napkins from the roll, the nozzle defining a nozzle cross-sectional area (A_(N)), wherein A_(N) divided by the web cross-sectional material mass (X) multiplied by a constant C=10,000, (A_(N)/X)*C is greater than or equal to about 0.85.

In other embodiments of the present invention, a method of supplying napkins for a center-pull type dispenser is provided. In various embodiments, the method comprises the steps of: i) providing a center-pull type dispenser comprising: a) a body for supporting at least one roll of perforated paper napkins; and b) a nozzle operatively connected to the body for dispensing the paper napkins from the roll, the nozzle defining a nozzle cross-sectional area (A_(N)); ii) providing at least one roll of perforated paper napkins, the paper napkins defining a scaled web cross-sectional material mass (X) wherein the ratio of the nozzle cross-sectional area (A_(N)) divided by the scaled web cross-sectional material mass (X) multiplied by a constant C=10,000 is about, (A_(N)/X)*C≧0.85; and, iii) placing said at least one roll of perforated paper napkins inside the body such that napkins may be dispensed via the nozzle.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 is a side view of a center-pull napkin dispenser according to various embodiments of the present invention;

FIG. 2A-2C are face-on views of nozzles according to various embodiments of the present invention;

FIG. 3 illustrates the geometry of a napkin, according to various embodiments of the present invention;

FIG. 4A-4B are front and side views of an unwrinkled napkin, according to various embodiments of the present invention;

FIG. 5A-5B are front and side views of a wrinkled napkin, according to various embodiments of the present invention;

FIG. 6A-6C are front views of napkins and their corresponding wrinkle index (W), according to various embodiments of the present invention; and

FIG. 7A-7F are graphs showing data illustrating the effect of the nozzle-paper ratio on the wrinkle index (W) for napkins dispensed through a center-pull napkin dispenser, according to various embodiments of the present invention.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

Structural Features of Various Embodiments

FIG. 1 shows a center-pull napkin dispenser 10 according to various embodiments. A center-pull napkin dispenser 10 may comprise a body 11 configured for supporting at least one roll of perforated paper napkins 20. A center pull napkin dispenser 10 comprises at least one nozzle 12 configured for dispensing paper napkins 25. In various embodiments, the center-pull napkin dispenser 10 is configured to control the amount of wrinkling of napkins dispensed by the center-pull napkin dispenser, as represented by a wrinkle index (W). Some of the features of various embodiments of the center-pull napkin dispenser 10 will be discussed in detail below.

Body 11

As shown in FIG. 1, the center-pull napkin dispenser comprises a body 11 configured for supporting at least one roll of perforated paper napkins 20. In various embodiments, the body 11 may be generally circular or elliptical in cross-section. In other embodiments, the body 11 may have a cross-section that is generally square, rectangular, or alternatively shaped.

In various embodiments, the body 11 may be made of plastic, metal or some other suitable material. In various embodiments, the body 11 may be configured to be mounted on a wall, ceiling, or the like. In other embodiments, the body 11 may be configured to rest on a table, counter, shelf or the like. In some embodiments, the body 11 may be configured such that the user may choose whether to mount the center-pull napkin dispenser 10 or set the center-pull napkin dispenser 10 on a table, counter, or the like.

In various embodiments, the body 11 may be configured to support one roll of paper napkins 20. In other embodiments, the body 11 may be configured to support two or more rolls of paper napkins 20. In various embodiments, the body 11 may comprise a selectively removable or hingedly removable door 14 that may be opened to place at least one roll of napkins 20 into the body 11. In other embodiments, a different mechanism may be used to position a roll of napkins 20 into the body 11, such as an opening at the top of the body. In still other embodiments, the body 11 may support at least one roll of napkins 20, but the napkins may not be placed inside the body 11.

In various embodiments, the body 11 may further comprise a fullness gauge 15 or window that may indicate how many napkins have been dispensed, how many napkins are still present on the roll of napkins 20, the percentage of the roll of napkins that has been dispensed, or may simply indicate when the supply of napkins supported by the body falls below a pre-determined threshold. The fullness gauge 15 may count the number of napkins dispensed, may measure the volume of napkins dispensed, may measure the volume or mass of the napkins remaining on the roll, or use some other suitable method to indicate when the supply of napkins supported by the body is running low.

It should be understood that a variety of variations of the body 11 are within the scope of the present invention.

Nozzle 12

Remaining with FIG. 1, and as noted above, a center-pull napkin dispenser 10 comprises a nozzle 12, and the nozzle 12 is operatively connected to the body 11. In various embodiments, the nozzle 12 is configured for dispensing napkins 25 from various locations on or adjacent to the body, such as on or in the bottom surface of the body. For example, the nozzle 12 could be on the top surface of the body 11 or in a side thereof, and could also be positioned at a distance from the body. In various embodiments, the nozzle 12 may be made of plastic, or metal, or some other suitable material.

FIGS. 2A-2C illustrate a variety of nozzles according to various embodiments. In various embodiments, the nozzle 12 may be generally circular or elliptical in cross-section. In some embodiments, the nozzle 12 may have a cross-section that is generally rectangular, rectangular with rounded corners, triangular, or alternately shaped.

The nozzle 12 defines at least one opening 121 disposed therein configured for dispensing napkins 25 from the at least one roll of napkins 20 supported by the body 11. In various embodiments, the nozzle opening 121 may be generally circular, triangular, or slot-shaped, such as generally elliptical, rectangular, or rectangular with rounded corners shaped. In other embodiments, the nozzle opening 121 may be “dog bone”-shaped or slot shaped with rounded ends wherein the nozzle opening is wider at the ends than in the middle of the slot. The nozzle opening 121 may have a variety of other shapes as well without departing from the scope of the present invention. In various embodiments, the nozzle opening 121 may further comprise projecting restrictions 122. The projecting restrictions 122 may have a variety of shapes in various embodiments. It should be appreciated that a wide variety of nozzle shapes are commonly known and understood in the art and may be used in various embodiments of the present invention.

The nozzle opening 121 defines a nozzle area (A_(N)). The nozzle opening 121 defines an effective diameter (D) that is the diameter of a circle having the same area as the nozzle opening 121. In various embodiments, the nozzle opening 121 may have an effective diameter (D) of about 0.40 inches, 0.53 inches, 0.63 inches, or 0.77 inches. In some embodiments, the nozzle opening 121 may have an effective diameter (D) in the range of 0.3 to one inch. As is discussed in detail below, the acceptable range of effective nozzle opening diameters (D) is determined by a lower limit wherein the napkin 25 separates from the web of paper napkins 20 before the napkin has been fully dispensed by the center-pull napkin dispenser 10 and an upper limit wherein the napkin does not separate from the roll of napkins when the napkin is dispensed by the center-pull napkin dispenser (i.e. “roping”).

In various embodiments, the shape or size of the nozzle opening 121 are not changeable. In other embodiments, the nozzle opening 121 may be adjustable in shape and/or nozzle cross-sectional area (A_(N)). In some embodiments, a spring-loaded bar that partially impedes the nozzle opening 121 may be used, allowing the center-pull dispenser 10 to accommodate rolls of napkins 20 of various basis weights. In other embodiments, a nozzle 12 may be removed and replaced with a nozzle 12 of the same or different nozzle opening shape and/or nozzle cross-sectional area (A_(N)). In other embodiments, the nozzle 12 may have more than one nozzle opening 121 and a user may select which nozzle opening 121 to dispense napkin 25 through.

In various embodiments, the nozzle 121 may further comprise a blade or cutting or ripping device (not shown) configured for helping separate an individual napkin 25 from the roll of napkins 20 as the napkin 25 is dispensed. In other embodiments, the roll of paper napkins 20 may be sufficiently perforated that a blade or cutting or ripping device may not be needed to separate an individual napkin 25 from the roll of napkins 20 as the napkin 25 is dispensed.

Napkin 25

A variety of paper webs are commonly known and understood in the art that may be used to make various embodiments of a napkin 25. For example, in various embodiments, napkin 25 may be made from a single ply web. In other embodiments, napkin 25 may be made from a double ply web, or even more plies. In various embodiments, napkin 25 may be embossed. In other embodiments, napkin 25 may not be embossed. In some embodiments, the napkin 25 may be a beverage or cocktail napkin. The paper web from which napkin 25 is made may define a web width (w_(w)). In various embodiments, the napkin 25 may be about six and a half inches (w_(w)=6.5″) in width. In other embodiments, for example when napkin 25 is a beverage napkin, the napkin may be about four and a half to five and a quarter inches wide (w_(w)=4.5-5.25″). For example, in certain embodiments, the napkin 25 may have a width of about five to eight inches (w_(w)=5-8″) or about four and a half inches to eight inches (w_(w)=4.5-8″). In other embodiments, the napkin 25 may be four to six and a half inches (w_(w)=4-6.5″) in width. In still other embodiments, the napkin 25 may be greater than six and a half inches (w_(w)>6.5″) in width. For example, in certain embodiments, the napkin 25 may be six and a half to nine inches (w_(w)=6.5-9″) wide or nine inches to twelve inches (w_(w)=9-12″) wide. The length of a napkin (l) is determined by the spacing of perforations along the length of the paper web. In various embodiments, the length of napkin 25 may be about eight and a half inches (l=8.5″). For example, in certain embodiments, the napkin 25 may have a length of six to ten inches (l=6-10″). In other certain embodiments, the napkin 25 may have a length of four and a half to ten inches (l=4.5-10″). In other embodiments, the napkin 25 may be five to eight and a half inches (l=5-8.5″) long. In some embodiments, for example when the napkin 25 is a beverage napkin, the length of the napkin may be about four and a half to five and a quarter inches long (l=4.5-5.25″). In yet other embodiments the napkin 25 may be longer than eight and a half inches (l>8.5″) in length. In certain embodiments, the napkin 25 may be eight and a half to twelve inches (l=8.5-12″) or twelve to fifteen inches (l=12-15″) in length.

In various embodiments, the napkin 25 is pulled through the nozzle opening 121 at an angle due to its unwinding from the roll of perforated napkins 20. Therefore, the effective width (w_(e)) of the napkin from the perspective of the nozzle may be greater than the web width, or w_(e)≧w_(w). The effective width (w_(e)) may vary between various embodiments depending on various factors that may comprise: the relative positioning of the nozzle 12 to the roll of paper napkins 20, what portion of the trailing napkin is pulled through when a napkin 25 is dispensed, and/or the like. In various embodiments, there may also be a small variation in the effective width (w_(e)) depending on from where in the roll of napkins 20 the napkin 25 is pulled as a function of the open diameter at the center of the roll, at what point along the napkin the measurement is made, and/or the like. Finally the effective width (w_(e)) will vary slightly as a function of the instantaneous degree and direction of folding of the napkin as it is pulled through the nozzle 12.

As noted above, the web width (w_(w)) sets a lower bound for the effective width (w_(e)). In various embodiments the effective width (w_(e)) may be calculated as w_(e)=w_(w)/cos φ, as shown in FIG. 3. In various embodiments, the angle φ is typically 30-50°. In certain embodiments, it is possible that φ<30° or φ>50°. In the calculations completed herein, the effective width (w_(e)) of the napkin as it passes through the nozzle opening 121 is approximated as w_(e)=w_(w)/cos φ, wherein the angle φ=40°. It should be appreciated that a variety of other approximations of the effective width (w_(e)) may be used without departing from the scope of the invention.

The paper web from which napkin 25 is made may also define a web caliper or thickness (c_(w)) and a basis weight (b_(w)). An apparent density (d_(a)) of the web may be approximated as the basis weight divided by the web caliper or d_(a)=b_(w)/c_(w). From this, a cross-sectional material mass (X) of the web may then be defined as the napkin width times the apparent density, or X=w_(e)*d_(a). The applicant has discovered that the amount of wrinkling suffered by a paper napkin is related to the amount of paper that is pulled through a nozzle at any given time, and that the cross-sectional material mass (X) provides a valuable parameter for controlling the wrinkling of a paper napkin, although other measures of the cross-sectional material mass (X) or measures which capture the same or similar properties of napkin 25 may be employed based on the disclosure herein.

Wrinkle Index (W)

An objective measure of napkin wrinkling may be determined such that the level of wrinkling experienced by various napkins 25 may be compared. In various embodiments, a wrinkle index (W) for a napkin 25 may be determined by considering the number of wrinkles, the size of the wrinkles, the depth of the wrinkles, and/or other parameters.

FIGS. 4A-4B illustrate a front and side view of a projected area of an unwrinkled napkin 21 having the same length and width measurements as the effective length and width measurements of a corresponding projected area of a wrinkled napkin 22 illustrated in FIGS. 5A-5B. Due to the vertical variations caused by the wrinkles 23, the wrinkled napkin 22 will have a larger surface area than the unwrinkled napkin 21 for the same projected area. In other words, a wrinkled surface with the same effective length and width dimensions as a smooth, unwrinkled surface will have a larger surface area than the unwrinkled surface. Thus, comparing the surface area of the unwrinkled napkin 21 to the wrinkled napkin 22 provides an objective measure of the degree of wrinkling experienced by wrinkled napkin 22. Therefore, it is possible to define a wrinkle index (W) such that the wrinkle index is the surface area of the wrinkled napkin 22 (Aw) projected area minus the unwrinkled napkin 21 projected area (As) with that result divided by the surface area of the unwrinkled napkin 21 projected area (As), or expressed as W=[(Aw−As)/As]*100. Thus, in various embodiments, the wrinkle index (W) may be dimensionless. In other embodiments, the wrinkle index (W) may have various dimensions. Thus, it should be appreciated that, given the disclosure herein, a variety of measures of the wrinkling experienced by a napkin, paper product, or other sheet product could be used without departing from the scope of the present invention.

In various studies, the Applicant used a Taylor Hobson CLI 1000 scanning laser profilometer to determine the sample area (A_(s)) and the wrinkled napkin surface area (A_(w)). This instrument provides a non-contact, non-destructive technique to quantitatively measure surface topography. The data output by the CLI 1000 used in these studies were three dimensional surfaces. To gather the data, the napkin sample was placed on a glass slide and provided to the CLI 1000 for scanning. Due to the sensitivity of the CLI 1000, a low-pass Gaussian filter, as defined according to the ISO 11562 standard, with a cut-off wavelength of 3.5 mm was applied to the raw data to distinguish the wrinkling of the napkin from the fiber-level roughness and/or embossment of the napkin.

FIGS. 6A-6C show three wrinkled napkin samples and the measured wrinkle index for each sample. As can be seen from FIG. 6A, a wrinkle index of W>2.5 indicates the napkin is very wrinkled, and, depending on the intended use, likely too wrinkled to be pleasing to a consumer. FIGS. 6B and 6C show that a wrinkle index of W<1.0 indicates a much less wrinkled napkin than a wrinkle index of W>2.5. For various applications, a consumer may find a napkin with a wrinkle index W<1.0 or W<0.5 to be acceptable and/or pleasing.

FIGS. 7A-7F show the measured wrinkle index (W) of various napkins 25 dispensed by various embodiments of a center-pull napkin dispenser 10. These data points were collected by using an Instron universal testing machine to apply a pulling-down force from a roll defining a vertical axis resulting in a maximum cross-head speed of 40 inches/minute. The force was applied directly down (i.e., with a deviation of 0 degrees from vertical) from the leading tip of the napkin 25 protruding from the center-pull dispenser 10.

FIGS. 7A-7F show how, in various embodiments, the wrinkle index (W) depends on the nozzle-paper ratio (R), wherein the nozzle-paper ratio is the nozzle cross-sectional area (A_(N)) divided by the napkin cross-sectional material mass (X) or R=A_(N)/X. The x-axes of FIGS. 7A-7F show the dimensionless scaled nozzle-paper ratio (R_(s)), wherein the scaled nozzle-paper ratio is the nozzle-paper ratio multiplied by a constant (C); thus, R_(s)=C*R=(A_(N)/X)*C. In FIGS. 7A-7F, the constant used is C=10,000. In other embodiments, different scaled nozzle-paper ratios may be defined that use various constants (C) and resulting in various units. In various other embodiments, a nozzle-paper ratio may be defined using the diameter (D) of a circle having the same area as the nozzle opening as a stand in for the nozzle cross-sectional area (A_(N)) or some other suitable description of size of the nozzle opening 121. Similarly, in other embodiments, the napkin cross-sectional area, napkin width, napkin volume, napkin density, or other parameter describing the amount of napkin 25 passing through the nozzle opening 121 at a given instant may be used in place of the napkin cross-sectional material mass (X). Thus, it should be appreciated that a variety of variations of the nozzle-paper ratio and the scaled nozzle-paper ratio disclosed herein may be defined without departing from the scope of the present invention.

FIGS. 7A-7D show the relationship between the wrinkle index (W) and the scaled nozzle-paper ratio (R_(s)) for a variety of napkins 25 with varying basis weight and caliper measurements. FIGS. 7D-7F show the relationship between the wrinkle index (W) and the scaled nozzle-paper ratio (R_(s)) for a variety of napkins 25 with varying bond areas, wherein the bond area describes the amount of perforation between two consecutive napkins on a roll of napkins. The bond area describes the percentage of the total width of a web remaining along a line of perforation separating two napkins after the perforations have been made across the web.

TABLE 1 Basis Weight 8 sheet caliper Bond Area Figure lbs/ream inches % 7A 16 0.048 5.2 7B 25 0.097 12 7C 26 0.137 12 7D 25 0.08 6 7E 25 0.08 7 7F 25 0.08 8.5

Table 1 provides the basis weight, caliper, and bond area for the napkins used in the trials in which the data used to produce FIGS. 7A-7F was collected. The width and length of all napkins used in these trials was six and a half inches (6.5″) and eight and a half inches (8.5″), respectively, and nozzle configured as in FIG. 2A was used.

For the trials illustrated in FIGS. 7A-7F, the wrinkle index (W) tends to decrease with increasing scaled nozzle-paper ratio (R_(s)). Thus, in various embodiments, the wrinkling experienced by a napkin 25 being dispensed from a center-pull napkin dispenser 10 may be controlled by choosing an appropriate scaled nozzle-paper ratio (R_(s)) for the intended application.

Surprisingly, the wrinkle index (W) does not have a linear relationship with the scaled nozzle-paper ratio (R_(s)) and decreases drastically with increasing scaled nozzle-paper ratio (R_(s)) only until a bend in the curve. For example, in FIG. 7A, the wrinkle index decreases at a steep slope until the scaled nozzle-paper ratio is about R_(s)≧0.85. Beyond this point, the wrinkle index (W) does not improve significantly and the napkin exhibits a satisfactory wrinkling index for some consumer applications. In other embodiments, a center-pull napkin dispenser 10 may be configured such that the scaled nozzle-paper ratio is R_(s)≧0.95. In still other embodiments, a center-pull napkin dispenser 10 may be configured such that the scaled nozzle-paper ratio is R_(s)≧1.2 or even R_(s)≧1.3.

The acceptable range of the scaled nozzle-paper ratio (R_(s)) is determined by various factors that may include the basis weight (b_(w)), web caliper (c_(w)), bond area, and/or nozzle cross-sectional area (A_(N)). If the scaled nozzle-paper ratio (R_(s)) is too small, the napkin 25 may separate from the roll of napkins 20 before the napkin 25 fully passes through the nozzle opening 121. If the scaled nozzle-paper ratio (R_(s)) is too large, the napkin 25 may not separate from the roll of napkins 20 as the napkin 25 passes through nozzle opening 121 (i.e., roping). Thus, the scaled nozzle-paper ratio (R_(s)) must be within the range that the napkin 25 will separate from the roll of napkins 20, but will not separate from the roll of napkins too early in the dispensation process. In various embodiments, the scaled nozzle-paper ratio is R_(s)≦2.15. The shape of nozzle opening 121 may also affect the roping or early tearing characteristics of a roll of napkins 20 dispensed from a center-pull napkin dispenser 10.

In various embodiments, the scaled nozzle-paper ratio (R_(s)) of a center-pull napkin dispenser 10 may be configured to dispense napkins 25 with a predetermined upper limit for the wrinkle index (W) for the napkins 25. For example, in various embodiments, the scaled nozzle-paper ratio (R_(s)) may be configured such that the wrinkle index (W) of a substantial number of paper napkins 25 dispensed by the center-pull napkin dispenser 10 is W≦1.5, 1.0, 0.8, or 0.5.

FIGS. 7A-7F illustrate how for paper napkin rolls made from various webs having a variety of basis weights, web calipers, various perforation bond areas, and/or other various web or napkin characteristics, a scaled nozzle-paper ratio (R_(s)) may correspond to preferred expected wrinkle index (W_(x)) given a nozzle 12. Thus, in various embodiments, a center-pull napkin dispenser 10 may be configured such that the scaled nozzle-paper ratio may provide an expected wrinkle index of W_(x)≦1.5, 1.0, 0.8, or 0.5.

Exemplary Methods of Supplying Napkins in Various Embodiments

Various embodiments of methods of supplying napkins for a center-pull napkin dispenser 10 will now be discussed. Of course, it should be appreciated that a variety of methods for supplying napkins for a center-pull napkin dispenser 10 could fall within the scope of the invention given the disclosure contained herein.

In various embodiments, a nozzle 12 is selected that comprises a nozzle opening 121 configured for dispensing napkins therethrough. The nozzle opening 121 may be selected to define a nozzle cross-sectional area (A_(N)) and/or a diameter (D) that corresponds to a diameter of a circle having the same area as the nozzle cross-sectional area (A_(N)).

Further, in various embodiments, a roll of paper napkins is selected that defines a web width (w_(w)), a web caliper (w_(e)), and a basis weight (b_(w)). In various embodiments the length (1) of a paper napkin 25 is defined by the perforations present on the roll of paper 25. As discussed above, the effective width (w_(e)) is approximated as w_(e)=w_(w)/cos φ, where φ=40°, herein; however, other various approximations of the effective width could also be used without departing from the scope of the present invention. The apparent density (d_(a)) of the napkin 25 may be approximated, in various embodiments, by the basis weight divided by the web caliper, or d_(a)=b_(w)/c_(w). Thus, in various embodiments, a cross-sectional material mass (X) for napkin 25 may be approximated as the product of the effective width and the apparent density, or X=w_(e)*d_(a).

In various embodiments, at least one roll of paper napkins may then be selected such that the nozzle-paper ratio (R), defined by the nozzle cross-sectional area (A_(N)) divided by the cross-sectional material mass (X), or R=A_(N)/X, is within a predetermined range. In various embodiments, the at least one roll of paper napkins may be selected such that the scaled nozzle-paper ratio (R_(s)), defined as the nozzle-paper ratio (R) times a constant (C), or R_(s)=(A_(N)/X)*C, is above a minimum value. For example, in embodiments in which the constant C=10,000, the scaled nozzle-paper ratio may be selected to be R_(s)≧0.85, 0.95, 1.2, or 1.3. In some embodiments, a roll of paper napkins 20 may be selected such that the wrinkle index (W) of a substantial number of paper napkins 25 dispensed by the center-pull napkin dispenser 10 is W≦1.5, 1.0, 0.8, or 0.5. In other embodiments, a roll of paper napkins may be selected such that the expected wrinkle index (W_(x)) of napkins that may be dispensed from the center-pull napkin dispenser 10 is W_(x)≦1.5, 1.0, 0.8, or 0.5.

The range of acceptable scaled nozzle-paper ratio (R_(s)) is limited by the ability of the center-pull napkin dispenser 10 to dispense napkin 25. If the scaled nozzle-paper ratio (R_(s)) is too small, the napkin 25 may separate from the roll of napkins 20 before the napkin 25 has been dispensed through the nozzle opening 121. If scaled nozzle-paper ratio (R_(s)) is too large, the napkin 25 will not separate from the roll of napkins 20 when the napkin 25 is dispensed (i.e., roping). However, the minimum and maximum acceptable nozzle-paper ratio (R_(s)) may be a function of the basis weight (b_(w)), caliper (c_(w)), bond area, nozzle cross-sectional area (A_(N)), and/or nozzle shape. In various embodiments, the scaled nozzle-paper ration is R_(s)≦2.15.

In various embodiments, the at least one roll of paper napkins 20 may be placed inside the body 11 of the center-pull napkin dispenser 10 such that napkins 25 may be dispensed from the roll of paper napkins 20 via the nozzle 12.

CONCLUSION

Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which this invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. 

That which is claimed:
 1. A center-pull type dispenser for dispensing paper napkins, the dispenser comprising: a body for supporting at least one roll of perforated paper napkins, the paper napkins defining a scaled web cross-sectional material mass (X); and, a nozzle operatively connected to the body for dispensing the paper napkins from the roll, the nozzle defining a nozzle cross-sectional area (A_(N)), wherein A_(N) divided by the web cross-sectional material mass (X) multiplied by a constant C=10,000, (A_(N)/X)*C is greater than or equal to about 0.85.
 2. The center-pull dispenser of claim 1 wherein the nozzle cross-sectional area (A_(N)) divided by the scaled web cross-sectional material mass (X) multiplied by the constant (C), (A_(N)/X)*C, is greater than or equal to 0.95.
 3. The center-pull dispenser of claim 1 wherein the nozzle cross-sectional area (A_(N)) divided by the scaled web cross-sectional material mass (X) multiplied by the constant (C), (A_(N)/X)*C, is greater than or equal to 1.2.
 4. The center-pull dispenser of claim 1 wherein the nozzle cross-sectional area (A_(N)) divided by the scaled web cross-sectional material mass (X) multiplied by the constant (C), (A_(N)/X)*C, is greater than or equal to about 1.3.
 5. The center-pull dispenser of claim 1 wherein the scaled web cross-sectional material mass (X) multiplied by the constant (C) is no greater than about 2.15.
 6. The center-pull dispenser of claim 1 wherein the nozzle defines a cross-section that is a circle.
 7. The center-pull dispenser of claim 1 wherein the nozzle defines a cross-section that is a slot.
 8. The center-pull dispenser of claim 1 wherein the nozzle defines a cross-section comprising projecting restrictions.
 9. The center-pull dispenser of claim 1 wherein a diameter (D) of a circle having the same area as said nozzle cross-sectional area (A_(N)) is selected from the group consisting of about 0.40 inches, about 0.53 inches, about 0.63 inches, and about 0.77 inches.
 10. The center-pull dispenser of claim 1 wherein a diameter (D) of a circle having the same area as the nozzle cross-sectional area (A_(N)) is about 0.3 to 1 inch.
 11. The center-pull dispenser of claim 1 wherein said at least one roll of perforated paper napkins has a web width of about four and a half inches to about eight inches.
 12. The center-pull dispenser of claim 1 wherein said at least one roll of perforated paper napkins comprises perforations that define a napkin length of four and a half to ten inches.
 13. A method of supplying napkins for a center-pull type dispenser, the method comprising the steps of: i) providing a center-pull type dispenser comprising: a) a body for supporting at least one roll of perforated paper napkins; and b) a nozzle operatively connected to the body for dispensing the paper napkins from the roll, the nozzle defining a nozzle cross-sectional area (A_(N)); ii) providing at least one roll of perforated paper napkins, the paper napkins defining a scaled web cross-sectional material mass (X) wherein the ratio of the nozzle cross-sectional area (A_(N)) divided by the scaled web cross-sectional material mass (X) multiplied by a constant C=10,000, (A_(N)/X)*C, is greater than or equal to about 0.85; and, iii) placing said at least one roll of perforated paper napkins inside the body such that napkins may be dispensed via the nozzle.
 14. The method of claim 12 wherein the ratio of the nozzle cross-sectional area (A_(N)) divided by the web cross-sectional material mass (X) multiplied by the constant (C), (A_(N)/X)*C, is greater than or equal to about 0.95.
 15. The method of claim 12 wherein the ratio of the nozzle cross-sectional area (A_(N)) divided by the web cross-sectional material mass (X) multiplied by the constant (C), (A_(N)/X)*C, is greater than or equal to about 1.2.
 16. The method of claim 12 wherein the ratio of the nozzle cross-sectional area (A_(N)) divided by the web cross-sectional material mass (X) multiplied by the constant (C), (A_(N)/X)*C, is greater than or equal to about 1.3.
 17. The method of claim 13 wherein the scaled web cross-sectional material mass (X) multiplied by the constant (C) is no greater than about 2.15.
 18. The method of claim 13 wherein the nozzle defines a cross-section that is a circle.
 19. The method of claim 13 wherein the nozzle defines a cross-section that is a slot.
 20. The method of claim 13 wherein the nozzle defines a cross-section comprising projecting restrictions.
 21. The method of claim 13 wherein a diameter (D) of a circle having the same area as said nozzle cross-sectional area (A_(N)) is selected from the group consisting of about 0.40 inches, about 0.53 inches, about 0.63 inches, and about 0.77 inches.
 22. The method of claim 13 wherein a diameter (D) of a circle having the same area as the nozzle cross-sectional area (A_(N)) is about 0.3 to 1 inch.
 23. The method of claim 13 wherein said at least one roll of perforated paper napkins has a web width of about four and a half inches to about eight inches.
 24. The method of claim 13 wherein said at least one roll of perforated paper napkins comprises perforations that define a napkin length of four and a half to ten inches. 